This application is in response to NIMH PAR-14-008, ?Secondary Data Analyses to Explore NIMH Research Domain Criteria RDoC (R03).? This application proposes to use existing data in two large longitudinal data sets that began in the preschool period to investigate Affective social communication (ASC) and it's neural correlates in childhood affective disorders. ASC is a sub-category of the RDoC ?Systems for Social Processes? Domain and is defined as the ability to effectively communicate, interpret, and experience affect in the context of social interactions. Deficits in ASC are associated with impaired functioning in school, family, and peer relations and have been documented in young children with affective psychopathology. While ASC has been a primary target of investigation in Autistic Spectrum Disorders, our current understanding of the nature of impaired ASC and its underlying neural circuitry in children with affective disorders remains highly limited despite its clinical significance. A network of brain regions ? referred to as the `social brain' ? that supports affective social behaviors has been identified and is known to undergo significant structural, functional, and connectivity changes during adolescent development. This is also a time of heightened social awareness and peer engagement as well as risk for affective disorders. A goal of this proposal is to investigate the relationships between typical to and atypical ASC abilities at multiple timepoints in early childhood using separate community-based (ages 3 and 6) and clinically-enriched (ages 3-5, and 6-8) samples. The relationship of these early ASC skills to the occurrence, course, and severity of affective psychopathology through middle childhood and adolescence will be investigated. A further central focus is to test whether childhood ASC skills are associated with disrupted neural circuitry in the `social brain network' during later childhood and adolescence. Using 3 waves of scan data available in one of the samples (obtained during later childhood and adolescence) change in functional, resting-state connectivity, and structural MRI scans will also be investigated as a function of early childhood ASC. We will also test whether neural markers mediate the relationship between early childhood ASC and later affective psychopathology. ASC represents a clinically important but under-investigated domain in affective disorders. This application will utilize two unique complementary existing longitudinal datasets to conduct secondary analyses in order to fill this gap in the literature.